gogachinchaladze February 2016

Keydown Which Not Working Chrome Extension

I've been struggling with my idea of google extension, and you as always are the last hope of mine ! :))

Well, I want to click the button on my chrome extension that will cause keydown simulation on the page extension is running.

I think chrome has some safety issues on my idea, that blocks the keyboard simulation (makes event isTrusted:false) and deletes which property.

The function I wrote works fine on jsfiddle , but it appears that chrome extension does it in a different manner.

Here is the content script file :

chrome.runtime.onMessage.addListener(function (request, sender, sendResponse) {
  if(request.action == "scrollToTop"){

  }
  else if(request.action == "scrollToBottom"){

  }
  else if(request.action == "enter"){
    triggerKeyboardEvent(document,13);
  }

  function triggerKeyboardEvent(el, keyCode){
    var event = new Event("keydown", {"bubbles":true, "cancelable":true});
    event.which = keyCode;
    el.dispatchEvent(event);
  }

});
chrome.runtime.sendMessage({action : "show"});

The log on jsFiddle writes:

Event {isTrusted: false, which: 13}

The log on website:

document.addEventListener('keydown',function (e) {
      console.log(e)
}

writes just:

Event {isTrusted: false}

Answers


gogachinchaladze February 2016

Thanks to @BG101 and @Rob W I found out that solution is script injection!

the only thing was that according to MDN KeyboardEvent.initKeyboardEvent() is depricated, so I replaced the code with:

var event = new Event(event, {"bubbles":true, "cancelable":true});

Also, as I wanted the trigger to run on document, I removed the element selector things. Here is what I got:

chrome.runtime.onMessage.addListener(function (request, sender, sendResponse) {
  if(request.action == "scrollToTop"){
    triggerKeyboardEventOnDocument("keydown",38);

  }
  else if(request.action == "scrollToBottom"){
    triggerKeyboardEventOnDocument("keydown",40);

  }
  else if(request.action == "enter"){
    triggerKeyboardEventOnDocument("keydown",13);
  }

  function triggerKeyboardEventOnDocument(event, keyCode){
    var script = document.createElement('script');

    script.textContent = '(' + function(event, charCode) {

        //Create Event
        var event = new Event(event, {"bubbles":true, "cancelable":true});

        // Define custom values
        // This part requires the script to be run in the page's context
        var getterCode = {get: function() {return charCode}};
        var getterChar = {get: function() {return String.fromCharCode(charCode)}};
        Object.defineProperties(event, {
          charCode: getterCode,
          which: getterCode,
          keyCode: getterCode, // Not fully correct
          key: getterChar,     // Not fully correct
          char: getterChar
        });
        document.dispatchEvent(event);
      } + ')(' + '\"' + event + '\", '+ keyCode + ')';

    (document.head||document.documentElement).appendChild(script);
    script.parentNode.removeChild(script);
  }

});
chrome.runtime.sendMessage({action : "show"});

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Asked in February 2016
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